In known tool turrets of this type the toothed rims of the tool turret and the turret housing, as well as the tooth construction of the position-locking member, are configured as standard Hirth-type serrations with a 60.degree. angle between the flanks of each serration. The piston is acted upon by hydraulic oil. The hydraulic power source producing force for pressing the position-locking member against the two toothed rims is advantageous since the effective piston surface can be relatively small. This advantage decreases the overall dimensions of the tool turret.
On the other hand, it is disadvantageous that a hydraulic system, to which the tool turret can be attached, must be present. The high pressure lines required between this hydraulic system and the tool turret and the piston together with the cylinder holding it form a heat source inside the tool turret. Such heat source leads to undesirable heat expansions, negatively effecting the precision of the processing.